Apparatus for processing bituminous sands

ABSTRACT

THE PRESENT INVENTION PROVIDES NEW AND IMPROVED APPARATUS FOR PROCESSING BITUMINOUS SANDS TO RECOVER PETROLEUM. THE APPARATUS IS PREFERABLY A MULTI-CELL STRUCTURE PRINCIPAL CELLS OF WHICH INCLUDE BOTTOM STIRRER ZONES AND UPPER QUIET ZONES SEPARATED FROM THE STIRRE ZONES BY BAFFLES. CONTINUOUS THROUGH-PLANT FEED IS PROVIDED FOR THE PLANT STRUCTURE BY PARTIALLY PROCESSED SANDS BEING URGED INTO SUBSEQUENT CELLS FOR CONTINUED PROCESSING. AN OIL SLICK FORMS THE UPPER SURFACES OF THE FLUID LEVELS IN EACH CELL AND THE SO-FORMED OIL SLICK GRADUALLY SPILLS OVER INTO COLLECTION TROUGH. NOVEL IMPELLER OR STIRRER MEANS ARE PROVIDED TO PROVIDE THE REQUISITE, SLIGHT AGIATATION AT THE BOTTOM OF EACH CELL FOR OIL SEPARATION AND YET RETAIN THE STIRRED MIXTURE AT THE BOTTOM OF THE CELL TO THE BOTTOM ZONE OF EACH CELL AFFECTED. ADJUSTABLE GATE MEANS ARE PROVIDED ACCOMMODATE REGULATION OF FEED-THROUGH THROUGH THE PLANT STRUCTURE.

Sept. 20, 1971 5 BRlMHALL 3,695,975

APPARATUS FOR PROCESSING BITUMINOUS SANDS Filed March 5, 1969 2 Sh60tl-$h0t 1 N In 8 INVENTOR.

RAY $.BRIMHALL 3 ms ATTORNEY Sept. 20, 1971 s, BRMHALL 3,605,975

APPARATUS FOR PROCESSING BITUMINOUS SANDS Filed March 5, 1969 2 Shattl-Shcct 2 INVENTOR.

RAY S. BRIMHALL HIS ATTORNEY United States Patent Office Patented Sept. 20, 1971 3,605,975 APPARATUS FOR PROCESSING BITUMINOUS SANDS Ray S. Brimhall, 4604 Idlewild Road, Salt Lake City, Utah 84117 Filed Mar. 3, 1969, Ser. No. 803,749 Int. Cl. B01d 12/00 US. Cl. 196-1452 Claims ABSTRACT OF THE DISCLOSURE The present invention provides new and improved apparatus for processing bituminous. sands to recover petroleum. The apparatus is preferably a multi-cell structure principal cells of which include bottom stirrer zones and upper quiet zones separated from the stirrer zones by bafiies. Continuous through-plant feed is provided for the plant structure by partially processed sands being urged into subsequent cells for continued processing. An oil slick forms the upper surfaces of the fluid levels in each cell and the so-formed oil slick gradually spills over into a collection trough. Novel impeller or stirrer means are provided to provide the requisite, slight agitation at the bottom of each cell for oil separation and yet retain the stirred mixture at the bottom of the cell to the bottom zone of each cell affected. Adjustable gate means are provided to accommodate regulation of feed-through through the plant structure.

The present invention relates to equipment for processing bituminous sands to recover petroleum therefrom and, more particularly, to a new and improved apparatus providing for formation of one or more surface oil slicks which may be combined into a single recovery system.

The history and recent development of recovery of heavy petroleum from bituminous sands is of keen present interest.

By way of definition bituminous sands are bulk sands impregnated with a heavy petroleum. Early observers named discovered bituminous sands as tar sands because of the asphaltic appearance of the sand deposits. Geologists later referred to these sands as oil sands since their interest lay in the bituminous sands as a possible source of oil. Through long usage, the term tar sand will probably persist in the art as the proper term for these sands. However, since the sands contain a heavy petroleum, bituminous sands is deemed the favored term and will be used herein.

Bituminous sands are found in most areas of the World where petroleum is located. It is noted that when oil wells in petroleum fields cease to produce, many countries return to underground workings at the oil field to recover the petroleum from the sands surrounding the oil fields.

The largest known deposit of bituminous sands are the Athabasca bituminous sands which lie in the northern part of the province of Alberta in Canada. These outcrop along the Athabasca River north of McMurray.

In the United States large deposits of bituminous sands are found in California and Utah as well as certain other states.

The Athabasca bituminous sand deposit is known geologically as the McMurray Foundation and is of the Lower Cretaceous age. It lies uniformly on Devonian limestone and shale of the Upper Devonian age, and is overlain by the Clear Water formation, a formation of marine shales. The McMurray formation comprises bituminous and fine-grained sands, is characterized by erosional disconformity, and includes some clay and shales.

In the United States principal deposits are the Edna deposit near San Luis Obispo, Calif, the Vernal deposits which are located near Vernal, Utah, and are outcroppings along the Green River, and the Sunnyside, Utah deposits.

Various types of recovery treatment and apparatus have been used in connection with the Athabasca bituminous sands and pre-date experimental methods of recovery in the United States. Most of the procedures heretofore used in Canada have been employed on somewhat an experimental basis in the United States.

In Athabasca bituminous sands soluble salts in significant quantity are absent. Where such salts are present as in certain California bituminous sands, the salts have to be leached out before separation can be effected. Extensive investigation with the Athabasca bituminous sands has revealed a thin film of water separates the oil from the sand grain surfaces. Hence, the primary problem is really not one of separation of the petroleum from the sands but rather of concentration.

One technique which has been used heretofore in connection with the recovery of petroleum from Athabasca bituminous sands is the so called Hot-Water Washing Method. Any procedure which treats bituminous sand With warm or hot water results in the oil drawing away from much of the sand and forming oil clots. These oil clots will frequently enmesh sand particles. A practical problem, hence, is to devise a procedure and structure which will result in a withdrawal and separation of oil from the sand and, in the process, collecting a minimum of mineral matter. One must recall that the specific gravity of the heavy petroleum in the sands is greater than that of water.

One procedure used in connection with hot-water washing has been proposed and developed by the Research Council of Alberta. It includes the step of heating and mixing the bituminous sand into a pulp containing twelve to fifteen percent Water. The pulp is flooded with additional water in such a manner that a minimum entrainment of air is involved. (Entrainment of air at the point of flooding causes the production of a fluffy froth loaded with the sand particles. This is, of course, undesirable.) A froth is produced and this froth is removed by skimming. As to Athabasca sands, the froth contains about five percent by weight of mineral matter and also about thirty to thirty-five percent by weight of water. Optimum temperatures for this operation lie in the region of F.

In this particular process it has been noted that in the pulp described the petroleum oil will lie among the sand grains as oil flecks, all of which are small and some of which are exceedingly small. The size distribution of these flecks is related to the content of very rfine mineral matter in the oil sand. Any clay present in this material has a most potent effect. Some clay is usually required for proper fleck formation, but an excess amount will cause increasing formation of the very fine, hard to recover fine flecks.

On flooding the pulp with water, the coarser ones of the oil flecks will form bubbles and float to the surface. Very fine flecks do not form bubbles and remain suspended in the water. The gas phase of the froth exhibits properties of water vapor, as is to be expected, which is supplemented by air to increase pressure to that of the atmosphere.

Certain prior observation and experimentation have revealed the desirability of including an alkalizing agent in bituminous sand pulps to neutralize acidity. Acidity generally exists in most bituminous sands and actually increases when bituminous sands are subjected to prolonged storage.

Another type of hot water process which has been used both in Canada and in the United States consists in milling the bituminous sand and introducing the same into a mixer containing water. An alkalizing agent may be 1ntroduced either into the dry bituminous sand or into the water fed into the mixer. The bituminous-sand aqueous pulp is fed into a flotation cell to produce an oil-water froth. In this process there is used a source of compressed air which is fed into the bottom of the flotation cell so as to carry the heavy bituminous oil to the surface thereof. It is recalled that bituminous sands have a specific gravity which is greater than water. The oil-water froth is collected and circuited through a dryer and thence through a coker. The vapor and liquid oil at the coker is fed into a refinery, whereas bottoms from the coker are used as in-plant fuel. Sand collecting at the bottom of the flotation cell is fed into a sand-Water separator, the sand being discharged and the water therefrom fed back into the Water, bituminous sand mixer. In-plant fuel is used to fuel a heater which receives a portion of the water from the sand-Water separator and feeds in directly into the flotation cell.

Another technique that has been employed in connection with recovery of petroleum from bituminous sands is a Cold-Water Washing Method. This has been performed by at least one Canadian company near Mc- Murray, Canada. The principles involved in the cold-water treatment are straight forward. A distillate such as kerosine is mixed with the bituminous sand to increase the fluidity of the oil content, so it will flow readily at room temperatures, and also to reduce its density below that of water so it will float. Also, an alkalizing agent and also a wetting agent are added to the pulp to assist in the disengagement of oil from the sand. The petroleum sand so treated is agitated in water. The diluted oil floats as a water-in-oil emulsion, and the mineral matter sinks. The oil is collected and then settled to reduce its content of mineral matter and Water.

In the cold-water process a net recovery of ninety-five percent of the oil in the bituminous sand treated was obtained. But final diluted oil product contained not only about two percent mineral matter but also twenty-five percent water.

Note is to be made that with the application of heat the bituminous oil becomes slightly less viscous, expands, and hence has a slight reduction in specific gravity. Further, hot Water results in the bituminous oil drawing away from much of the sand and forming oil clots.

As to the location and processing of United States bituminous sand deposits, those near the cities of Santa Cruz, San Luis Obispo and the town of Sisquoc in California have been estimated by the United States geological survey to contain over two hundred million barrels of oil. The Utah deposits near Vernal in the Uinta Basin and near the coal mining town of Sunnyside on the southern edge of the Uinta Basin include deposits which lie at elevations between nine and ten thousand feet near the top of Book Cliffs. It has been estimated that the Vernal deposit contains in excess of one billion barrels of bitumen. The Sunnyside deposit in Utah may contain nearly one billion barrels of bitumen. Hot 'Water separation tests as above described have been run in the San Francisco laboratory of the Bureau of Mines and various quarry samples of bituminous sands from the Edna deposits near San Luis Obispo and from Vernal and Sunnyside. Note has been made, in connection with the sandstones present in the California and Utah deposits, that recovery is enhanced through the well-known phenomenon that water, having a preferential wetta'bility for silica, will displace crude oil from quartz-sand grains and other siliceous particles. It has been discovered that certain alkaline solutions are more effective than plain water as a displacing medium; virtually entire displacement of the bitumen readily takes place when the water is alkaline 4- enough to neutralize any acidity that may be present in the bituminous sandstone.

In the case of the Edna sandstones which contain iron, calcium, sodium and aluminum sulfates, there is made necessary the process of a prior water-washing and hence leaching out the sandstones to remove these impurities;

unless removed, the salts present may react with alkaline reagents in the aqueous pulp and form gelatinous iron and calcium hydroxides and colloidal masses may form.

Results of separation tests in connection with the Edna deposits demonstrate that neutralization of the acidity of the bituminous sands containing sodium silicate or sodium carbonate is a fundamental requirement for complete displacement of the bitumen from the sand grains. The addition of a light-gravity fuel-oil diluent facilitates displacement of the bitumen. Removal of acid-iron salts greatly reduces the quantity of alkaline agents required to neutralize acidity in pulping. Hydrolysis of sulfates as may be present is frequently performed.

A satisfactory diluent to use in pulping sandstone and diluting the oil froth, to facilitate settling out of Water sand and silt, is one containing substantial quantities of aromatic compounds.

Careful control of pH in the treating system is important in processing the Edna as well as the Utah sandstones. An alkaline system kept at approximately 8 to 8.2 is deemed preferred.

Separation tests have been performed on the Vernal and Sunnyside bituminous sandstones in Utah. It has been found in connection with the Vernal formation that the bitumin is extracted more readily by the action of hot water than the Edna bitumen. This greatly simplifies plant operation. Vernal sandstone contains substantially no water-soluble iron compounds such as that in the Edna sandstone and therefore requires no preliminary washing. Through use of the applicants invention as described hereinafter, recovery of bitumen can be in excess of ninetyeight percent.

In contrast with the softness of the Edna and Vernal sandstones, the Sunnyside sandstone is extremely hard asphalt rock and must be crushed to small size to facilitate complete disintegration and displacement of the bitumen of the sand grains in pulping. It has been found that the disintegrated sand is fine and contains a large percentage of silt. This, absent the features in the present invention, will increase loss of bitumin to tailings discharged in the plant. In the case of prior developments, there has been a problem of refining the heavy petroleum or tar to get a satisfactory yield of end products. There have been recently new developments in the catalytic treatment of heavy oils with hydrogen to make the refining process more efiicient. All of these factors have combined to make the hot Water method above-described appear to be economically feasible.

The diluent used in the process followed with employment of the below-described apparatus may be removed by distillation.

Other methods for the recovery of petroleum from bituminous sands are continuous retorting and certain in situ methods.

As to continuous retorting, this has been used in Canada. The process is to retort the oil sand and then collect the cracked distillate; a fluidized solid bed in the reactor constituted the sand aggregate of the oil sands. Bituminous sand was fed from the top onto this bed. The oil passed into the gas stream as cracked oil vapors and carbonized sand joined the fluidized bed. The coke formed was burned off and the sand in the burner and hot sand was returned to the reactor. The method gave a yield of distillates of approximately eighty-five percent by volume of the oil in the bituminous sand feed. Specific gravity of the combined distillates was approximately .960 (16.0 API).

An apparent advantage of retorting the oil sand is that the fluid, transportable oil product was obtained by one operation. Normally oil in bituminous sand as obtained by the hot-water washing method is too viscous for handling and would need to be processed by coking or in some other way for commercial development.

As to in situ methods, the same have been considered where strip mining or surface mining are not entirely satisfactory. For example, as to the McMurray sands certain overburden conditions are adverse, except in restricted areas near the Athabasca River; where the deposit is too deep for conventional strip mining techniques, then, obviously, in situ recovery has to be considered. Certain companies such as the Sinclair Oil and Gas Company and the Magnolia Petroleum Company previously commenced work on certain underground, controlled-burning in heavy oil reservoirs. The method consists in drilling a pattern of holes on a five-spot plan, for instance, then setting fire to the oil sand at half the holes and collecting oil from the other half. Air under pressure and in a controlled amount contains combustion. The firefront distills the oil ahead of it and the fuel from the fire is mainly the coke deposited by the destructive distillation. The diluting action of the distillate formed, heat, and the pressure of combustion gases all act to make the heavy reservoir oil fluid and to cause it to move toward the output holes. Recovery of eighty-five percent of the oil in the bituminous sand has been achieved in laboratory burning tests. This method has been employed in actual oil reservoirs with encouraging results. To date no knowledge is has as to whether or not this burning method has been applied to Athabasca bituminous sands. Nonetheless, the possibility would be interesting since drilling costs would be low because of the shallow depth at which the bituminous lie. There is a serious question, however, whether the communication through the oil sand of both the shale free and interbedded varieties can be established and, if so, over what distances. There is a problem as to whether or not in actual, non-laboratory work, the method can be made to work.

The present invention comprises apparatus utilizing some of the desirable features heretofore known in other processes as above-pointed out and, additionally, provides means for assisting in the processing of bituminous sands in the manner described in the inventors co-pending application entitled, Method of Processing Bituminous Sands, Ser. No. 803,748, filed Mar. 3, 1969. The apparatus of the present invention is of multiple-cell construction the initial cells of which successively admit bituminous-sand feed and diluent, and the final cell of which is preferably a settling cell. Means are provided for advancing sand accumulations progressively through the cells for further processing. It is most important to note that the principal cells include stirring zones, quiet zones, and baflle means separating the two. Rather than the production of an oil-water froth or emulsion at the liquid surface of each cell as in the prior art, there is provided an oil slick that automatically pours over the edges of the respective cells to a collecting trough. A minimum amount of drying, if at all, is needed for the collected product. Appropriate means are provided for stirring the mixtures at the bottom of the primary cells and allowing the oil to ascend upwardly along circuitous paths through bafiie areas into quiet zones for oil-slick formation.

Accordingly, a principal object of the present invention is to provide new and improved apparatus for processing bituminous sands.

An additional object is to provide a multiple-cell processing plant whereby the sands may be treated in a continuous manner for a maximum recovery of petroleum therefrom.

An additional object is to provide a means for regulating feed flow through the multi-cell structure of the present invention.

An additional object is to provie a new impeller or stirrer system for bituminous sand treatment plants.

A further object is to provide baffie means in a bituminous sand treatment plant which separates the stirrer portion of the cells from the quiet zones thereof.

An additional object is to provide improved collection means for bituminous sand treatment plants.

An additional object is to provide a means in the subject structure for removing coagulants beneath resultant oil slick formations.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a petroleum sand treatment plant, constructed in accordance with the principles of the present invention, and is partly broken away for convenience of illustration.

FIG. 2 is a side elevation in reduced scale of the equipment illustrated in FIG. 1.

FIG. 3 is a transverse section taken along the line 33 in FIG. 2.

FIG. 4 is an enlarged fragmentary view of a representative bafiie system which may be used in the equipment of FIG. 1 to separate the stirring portion of a particular cell from its quiet zone.

FIG. 4A is a fragmentary view similar to FIG. 4 and illustrates an alternate bafile arrangement for construction which may be employed in lieu of that shown in FIG. 4.

FIG. 5 is a fragmentary plan view taken along the line 55 in FIG. 2 illustrating in plan the stirrer structure; for convenience of illustration the upper framing of the processing tank and the drive means associated therewith are deleted from this figure.

In FIG. 1 tank 10 is supported by legs 11 and includes partitions 12 for dividing the tank into three cells A, B, and C. For convenience of reference cells A and -B shall be referred to as primary recovery cells. Cell C may be considered as a settling cell or tank in which some secondary recovery of oil may occur. This will be explained hereinafter. As to cells A and B a plurality of baffie plates 14 are secured to the inner side walls of the tank 10, preferably in a stacked configured fashion as illustrated in FIG. 2. See also FIG. 3.

Disposed over the top of the tank and preferably welded to the upper side surfaces of partitions 12 is a bearing support angle 15. The latter mounts plural journal members 16 which receives stirrer shafts 17. Journal member 16 may comprise bushings, pillow-block bearings, or other suitable type of journaling means. The stirrer shafts 17 mount at their lower ends revolvable stirrers 18.

Stirrers 18 comprise individual units each having a central boss 19 pinned or otherwise secured to the lowermost extremity of its shaft 17. Affixed to the respective bosses 19 are stirrer paddles 20-23. Paddles 20-22 are preferably curved or arcuately formed as indicated to offset centrifugal action and optimize particle distributions in the water. Additionally, it is preferable that they be inclined forwardly in connection with their direction of travel, see FIGS. 1 and 5. When so formed, then they tend to stir or agitate slowly particles contained within the tank at the respective cells A and B and, in addition, to keep such stirred portions of the liquid mixture downwardly within the respective cells. One of the paddles 23 may be chosen to be straight, if desired, for successively urging accumulations at the bottom of the cell toward and through gate opening 24, see FIG. 3. Auger, interior conveyor belt, or other conventional means might be used equally as well in conveying sand droppings from one cell to a next adjacent cell, then to a third cell, and so on.

In the above regard it is seen that each of the partitions 12 includes a respective gate opening 24 over which is disposed movable gate 25. The latter may be secured to a gate actuating rod 26 having ring or handle 27. The gate, hence, may be positioned in accordance with the pinning of shaft 26, at a respective aperture 28 thereof, to aperture 29, a positioning aperture located in each respective partition. This may be accomplished by a pin or removable key 30, the latter preferably being secured by flexible chain 31 to rivet or screw 32 aflixed to the respective partition. Accordingly, the gate may be selectively raised and lowered to new positions so as to uncover a selected portion of the gate 24 opening. This in turn will predetermine the feed rate of material accumulations proximate the lower portion of cell A and its advancement through the gate to cell B, then to gate C, and so on.

In returning to a consideration of the several stirrer paddles associated with each shaft 17, it is seen that the same preferably are perforate, forming a perforate grate or wire mesh which may be supported, for example, by a radially extending bar 29, of straight configuration relative to stirrer paddle 23, and arcuate support bars 30, 31 and 32 of blades or paddles 20 22. Each of the stirrer paddles includes the grates made of wire mesh or bar mesh as at 29, 30', 31' and 32, so as to supply respective perforate paddles. The reasons for inclusion of perforate paddles is to provide for maximum turbulence per incremental volume areas of the mixture at the bottom of each cell A and B without producing undue turbulence of the liquid level. While solid stirrer paddles may be employed, it is deemed preferable in operation of the system that the stirrer paddles be perforate. This is to provide the slight internal agitation needed to keep the oil flecks suspended and available for rising without causing marked undulations in the surface level of the cell. The gratings may be made of sufiicient thickness as to individual elements to provide suflicient forward movement of accumulations at the bottom of each cell A and B forwardly through their respective gates.

FIGS. -15 illustrate various bafile arrangements which may be employed in the structure. This is for the purpose of dividing the cells into quiet zones Q, baflle areas R, and stirring areas S. Each cell A and B may be partially baified or fully baflled. The term fully bafi'led refers to the situation wherein all upward movements of oil particles must assume circuitous paths in order to advance to the upper surface of the liquid contained with tank 10. In such event, the baflles may be overlapping and staggered as illustrated in one modification of the invention as shown in FIG. 4. Note bafiies 14A in this regard and the vertical projections of which overlap, with the central baffle including an aperture 36 for receiving a respective stirrer shaft 17. Alternatively, baflles 14B and 14B may be employed in each of the cells A and B to provide complete circuitous movement of rising oil particles or droplets as these advance upwardly through the liquid to the upper surface thereof.

Inlet hopper 37 is secured to the structure as by welding at 38 and communicates with opening 39 leading into the initial oil recovery cell A. Disposed to the left of the leftward partition 12 in FIG. 2 is the settling tank or settling cell C. The latter may include a depending floor include a depending floor area 38 forming an outwardly extending auger housing 39. The latter includes auger 40 which is journaled to the structure at 41 and 42 in preferably included liquid-seal glands 43 of conventional design. Auger 40 includes a drive shaft 43 upon which driven pulley 44 is mounted. Drive pulley 45 is keyed to shaft 46, the latter being an integral part of motor 47. Motor 47 is bracketed in place by brackets 48 and 49. These latter may support a mounting plate 50 to which the motor 47 is bolted or otherwise secured. The V-belt 51 intercouples drive pulley 45 with drive pulley 46.

Collecting trough 52 is formed either as a separate part or integral with the outermost side 53 of the processing tank 10. Trough 52 is shown to slope downwardly for optimum running condition, and the level of liquid is adjusted to within the entire tank such that the oil slick formed on the quiet upper surface of the included water will automatically spill over edge 54 into collecting trough 52.

Suitable bracing 55 may be provided for the auger housing 39 as shown. Shafts 17 each include respective pulleys 56 and 57 which are pinned thereto. V-belts 58 and 59 intercouple these pulleys with drive pulleys 60 and 61 as shown. These outer pulleys are keyed to shaft 61 the latter of which may be an extension of the motor shaft or motor 62. Motor 62 may be electrically driven or may comprise an internal combustion engine or fluid motor, as desired.

Optimum results are obtained when the fluid mixture in the tank of FIG. 1 is heated. Such heating can be eifectuated through the provision of a heating coil, or simply a U-configured steam line, seen in FIG. 2 to take the form of a hair-pin-configured line 65 proceeding through all of the cells of A, B and C and being connected to a steam heat generating source 66. Other forms of heating, of course, are possible. The steam line is deemed ideally placed in FIG. 2 wherein the same is shown to be disposed beneath the baflle areas. Thus, the area of agitation is that area which the oil particles or droplets are heated so as to assist the latter to rise to the top of the liquid contained in the cells.

For each of the cells there may be provided a fluid circuit including a filter 67 and lines 68 and 69 connected thereto and communicating with the interior of the tank immediately beneath the oil slick area of the tank. Filter 67 may include a pump so as to Withdraw colloidal or coagulant accumulations immediately beneath the slick, filter the same out by conventional appropriate means, and return the liquid phase back into the tank. If desired, each cell of the tank may be provided with the same, in the manner as shown in FIG. 2. It is to be noted that the liquid phase is returned to a substantial area beneath the portion of the liquid both at the oil slick and immediately therebeneath where the colloidals will form.

The apparatus operates as follows. Introduced in inlet hopper 37 is bituminous-sand feed stock. This feed stock comprises bituminous sand mixed with a diluent such as kerosene. The mixture feed-stock will contain from approximately six to approximately twenty percent diluent, depending upon the character of the specific bituminous sand to be processed as well as the petroleum cut selected as the diluent. Steam should not be introduced directly in the feed stock since this tends to produce too-early separation of the water film that separates bitumen from each sand particle, thereby causing the bitumen to stock to the sand particles. Also, the alkalizing agent should not be introduced into the pulp or slurry but rather into the processing tank directly, thereby avoiding bitumen reaction and thus merely preserving proper pH in the aqueous mixture within the tank. Preferably, the bituminous sand will have a maximum particle bulk size less than two inches in diameter. Steam is applied via source 66 so that the aqueous mixture within the tank is heated approximately to the boiling point of water for the altitude at which the apparatus is being used. As the bituminous sand, diluent oil, are deposited into initial cell A, the combined agitating action of the stirrer paddles as they are rotated about the vertical axis of shaft 17 serves to thoroughly intermix the aqueous mixture including the oil sand, diluent oil, and alkalizing agent. With the mixture being heated as by circuitous steam lines 65, the oil sand will tend to separate into the constituents of oil, water and sand. Sand will drop to the bottom of the cells A and B Whereas the additional water will tend to go into a vapor phase to rise to the top of the liquid within tank 10. The diluent will aid the oil particles, globules or droplets within the mixture also to advance upwardly since the diluent serves to decrease the specific gravity of the combined oil within the mixture so as to permit the oil to proceed upwardly. The sand, of course, drops to the bottom and is progressively urged through the gate of the right-hand partition 12 into the second cell B. At this point the process is continued to provide for a secondary recovery of oil from the sand. It is to be noted that as the oil rises and forms an oil slick on the upper surface of the liquid, the oil slick tends to spill over the edges 54 so as to deposit into collecting trough 52. The oil so collected in collecting trough 52 downwardly along the trough and into an optionally included drying stage, not shown. Subsequently, the oil may be employed as a heavy specificgravity crude or be routed to fractionating equipment, as desired. The stirrer paddles of the individual stirrers X keep the oil sand in suspension in the cells liquid mixture a sufficient time in order that the heat from the steam line 65 may co-act with the bulk water present thereat in releasing through the oil from the sand, permitting the oil to rise upwardly. The two stages A and B, hence, are substantially identical. The third cell C, is a settling cell permitting any residual oil to rise to the top and permitting the sand advanced through the system to drop down into the cavity in which the lower portion of auger 40 is disposed. Rotation of the auger by motor 47 cause the sand to be advanced upwardly and out of the discharge opening 68. It has been found through experiment that clean sand drops from 68 in some locales this is actually white sand usable as play yard sand, aggregate, and so forth.

The bafile system is selected so that the upper portions of each cell form quiet zones. This is necessary in order that the upper surface of the water is not disturbed. It will be recalled that it is this water which supports the film or slick of oil which forms on the upper surface of the water. Oil recovery is had where the surface is not disturbed and where the oil flows smoothly over the edge 54 in FIG. 1. It is noted that this invention does not rely upon the formation of froth or an oil-emulsion as in flotation-type equipment. Rather, the opposite is true. What is needed is a very quiet zone in which a nonundulating oil slick may be formed and increased as to depth so that the same may flow over edge 54 into collecting trough 52.

Filters F with their associated pumps (not shown for convenience of illustration) allow the discharge of colloidals or coagulates from immediately underneath the surface of the oil slick and a return of the liquid (water) phase back to the tank. This prevents the bottom of the oil slick from becoming gummed or otherwise intimately associated with forming colloidals. As a practical matter the maintenance of pH at about 8.2 within the tank will deter most colloidals from forming. Those which do form can be pumped out, filtered and discharged. In this connection, several conventional filters F including their respective pumps P may include suitable conventional selfcleaning apparatus.

What is had therefore is a machine especially suitable for recovering bituminous products i.e. oil from bituminous sands. The invention relies upon heating an aqueous mixture containing the oil sands and allowing the oil separated thereby to form at the top of a tank as a quiet slick or collection pool. Stirring at the base of the respective cells is prevented, by suitable baffles, from interferring with the upper, quiet regions of the respective cells. The agitation thus produces a forced suspension of oil sand for heat-processing and oil-separation, and this in a manner such that the uppermost column portion of oil liquid is maintained in a quiescent state so that a quiet, non-undulating oil slick may be formed on the upper surface of the water. The slick thus formed is then allowed to deposit into collecting trough 22.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and within the true spirit and scope of the invention.

I claim:

1. Apparatus for processing bituminous sands and including, in combination, cell means for receiving a bituminous sand diluent mixture, said cell means having a bottom interior zone, an upper quiet zone to facilitate formation of an oil slick thereat, and a bafile zone disposed between said bottom interior zone and said upper quiet zone, solely suspension stirrer means disposed in said bottom interior zone for agitating said mixture so as to maintain at least some of said bituminous sands in suspension for oil-separation, means for receiving said oil slick as forms in said cell means quiet zone, and overlapping bafile means disposed in said cell means baffle zone for reducing transmission of agitation turbulence present in said bottom interior zone into said quiet zone, said stirrer means comprising a vertical, axially revolvable shaft, perforate vertical paddle means transversely secured to said shaft and outwardly extending therefrom for revolvement in a horizontal plane, and means for rotating said shaft.

2. Structure according to claim 1 wherein said stirrer means is canted downwardly in the direction of movement.

3. Structure according to claim 1 wherein some of said paddle means are arcuately configured longitudinally and concave forwardly in the direction of movement thereof.

4. Structure according to claim 1 wherein said paddle means are inclined forwardly, relative to their cross-section, for stirring contents in a downwardly canted direction.

5. Structure according to claim 4 wherein said paddle means are perforate.

6. Structure according to claim 1 wherein said apparatus includes heating means disposed within said cell means beneath said bafile zone thereof.

7. Apparatus for processing bituminous sands and including, in combination, plural, interconnected cell means for receiving a bituminous sand mixture, each of said cell means having a bottom interior zone, an upper quiet zone to facilitate formation of an oil slick thereat, and a baffle zone disposed between said bottom interior zone and said upper quiet zone, horizontally movable, perforate stirrer means disposed in said bottom interior zone of each of said cell means for agitating said mixture so as to maintain at least some of said bituminous sand in suspension for oil-separation, means for receiving said oil slick as forms in said cell means quiet zone, and overlapping baflie means disposed in each of said cell means baffle zones for reducing transmission of agitation turbulence present in said bottom interior zone into said quiet zone of respective ones of said cell means.

8. Structure according to claim 7 wherein said cell means are mutually separated by partition means, said partition means including a gate opening disposed proximate the bottom thereof, and means for varying said gate opening.

9. Structure according to claim 7 wherein each of said stirrer means includes an upstanding shaft, means for journaling said shafts, means for rotating said shafts coupled thereto, said shafts including outwardly extending perforate paddle means respectively disposed within said bottom interior zones of said cell means and shaft bafiie means disposed above said paddle means and constituting a portion of said bafile means.

10. Structure according to claim 7 wherein said apparatus includes a settling cell proximate the discharge end of said apparatus and communicating with an intermediate one of said cell means, said settling cell including means for removing sand therefrom, said receiving means formation present in said settling cell.

References Cited UNITED STATES PATENTS Sisson 210219X Darby 210-208 Gurney 210208 Lawlor 210--208 Fenske et a1. 23310 10 12 2,743,999 5/1956 Binswanger 23-31O 2,792,289 5/1957 Wilson 23-310 3,366,551 1/1968 Kaso 210-219X NORMAN YUDKOFF, Primary Examiner D. EDWARDS, Assistant Examiner US. Cl. X.R. 

